1. Field of the invention
This invention relates to a fuel injecting apparatus and in particular to a fuel injecting apparatus used for injecting an amount of fuel under a high pressure to a cylinder of an engine.
2. Description of the Related Art
A conventional fuel injecting apparatus is disclosed in the Japanese Patent publication No. 2-190,682. The conventional fuel injecting apparatus, as shown in FIG. 2, includes a fluid passage 109, a pressure chamber 113 connected to the fluid passage 109, and a valve member 103 disposed between the fluid passage 109 and the pressure chamber 113 which is operated by an axial length change of a piezoelectric actuator 118. That is to say, when the actuator 118 is shrunk or contracted, pressure in the pressure chamber 113 decreases. Then, the valve member 103 is moved upward by the fuel pressure applied to a pressure receiving surface 111 and opens an injecting port 102, which results in the fuel injection from the injection port 102 into a combustion chamber of an engine.
On the other hand, when fuel pressure in the pressure chamber 113 becomes high upon extension of the actuator 118, the valve member 103 is moved downward by pressure in the pressure chamber 113 and closes the port 102. The fuel injection is terminated.
However, in the conventional fuel injecting apparatus, since the injecting port 102 is extended into the combustion chamber of the engine, the valve member 103 may be forced to open by the explosion in the combustion chamber of the engine, which results in an unexpected fuel injection from the injecting port 102. In addition, though the amount of fuel to be injected depends on the radius of the injecting port 102, the the radius of the injecting port 102 may be varied due to adhesion of carbon thereto or thermal change in the combustion chamber, which leads to an incorrect fuel injection.